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Context: The synthetic, tension-free midurethral sling was introduced in the 1990s as a surgical treatment for women with stress urinary incontinence (SUI). Several similar products are now available. The authors generated data comparing clinical outcomes of two midurethral sling procedures.

Results: The TVT and Uretex groups were similar with respect to age, parity, and incidence of prior anti-incontinence surgery. There was no significant difference in outcomes measured between the two groups in symptom improvement at 12-month follow-up.

Conclusion: The TVT and Uretex midurethral slings demonstrate similar short-term improvement and complication rates in a nonrandomized population of women with SUI.

In the mid-1990s, Ulmsten and Petros1 introduced the synthetic, tension-free, midurethral sling for the surgical treatment of women with stress urinary incontinence (SUI). Since the late 1990s, this modality has become the most common surgical intervention in the United States for this patient population.2-4

Several similar products are now available. However, all such products have the same basic surgical precept: placement of a synthetic mesh sling in the midurethral region without tension.2-4

Success rates are reported to be as high as 90%, with most procedures conducted on an outpatient basis.2-4 Serious complications, such as bowel perforation and large-vessel perforation, have been reported rarely.5-8

We present the results of two nonconcurrent case series of 100 female patients (N=200) undergoing surgical repair of SUI with a midurethral sling procedure. Intervention occurred between June 2002 and April 2004 at the University of Pennsylvania Medical Center in Philadelphia. All aspects of the study were reviewed and approved by the University of Pennsylvania Medical Center. Informed consent was obtained from all patients participating in the study.

Patients undergoing either a TVT or Uretex midurethral sling procedure for the management of SUI with intrinsic sphincteric deficiency were included in the present investigation. All subjects received a comprehensive preoperative urogynecologic evaluation, including a cotton-tipped swab test (ie, “Q-Tip Test”) of straining bladder-neck mobility. The following definitions of bladder neck hypermobility9 were used:

minimal, <30 degrees

severe, ≥30 degrees

All subjects in the present study were diagnosed with SUI and had preoperative multichannel urodynamic evaluations. Data on Valsalva leak point pressure (VLPP), a measurement of the minimal abdominal pressure required to produce urine leakage, were also recorded. A VLPP value of less than or equal to 60 cm H2O is used as the urodynamic criterion for the diagnosis of intrinsic sphincteric deficiency.10 The VLPP was obtained with subjects seated when the total infused volume of sterile water reached 150 cc. A midurethral sling was chosen for all subjects with a VLPP value less than 60 cm H2O.

The TVT group consisted of the first 100 consecutive patients with SUI directed by their physicians to receive only a midurethral sling as treatment. The Uretex group consisted of the next 100 consecutive patients meeting the same inclusion criteria.

The same surgical team performed the intervention for both groups, following the standardized manner recommended by the manufacturers of each product, respectively—including passage of the trocars from the vaginal side to the abdominal side. Intraoperative cystoscopy was used for all subjects to evaluate any possible damage to the urinary tract from sling insertion.

In the recovery room before subjects were discharged to home care, a voiding trial was conducted to assess the need for prolonged bladder drainage. Subjects who voided a minimum of 100 cc urine and who had a postvoid residual urine volume of less than 100 cc were discharged without a Foley catheter.

Subjects who were unable to void 100 cc urine or who had a postvoid residual urine volume of 100 cc or greater were discharged from the hospital with an indwelling Foley catheter. Although routine postoperative follow-up for all subjects included office visits at 6 weeks, 3 months, and 12 months, individuals who received this catheter were evaluated in the outpatient office 48 hours after surgery—at which time the voiding trial was repeated. If further bladder drainage was deemed necessary, the subject was instructed in intermittent self-catheterization.

Data were collected prospectively from subjects regarding perioperative and postoperative complications. Perioperative complications were defined as bladder perforation, hemorrhage requiring blood transfusion, ureteral or urethral injury, and bladder drainage with indwelling Foley catheter for more than 4 hours. Postoperative complications were defined as the need for intermittent self-catheterization after postoperative day 2 (lasting less than 14 days total); urinary tract infection within 4 weeks after surgery; urinary retention requiring revision of the sling and urethrolysis; and new-onset postoperative urge incontinence. Objective outcomes were assessed at the 12-month postoperative visit using a standing bladder stress test. With a bladder volume greater than or equal to 250 cc of urine, subjects were observed for urine leakage when performing a standing Valsalva maneuver (ie, cough stress test).

Statistical analysis of outcome data consisted of 2-tailed t tests for continuous variables and either 2-tailed χ2 tests or Fisher exact tests (depending on the outcome/complication being evaluated) for dichotomous variables. All P values less than .05 were considered statistically significant. All statistical analyses were performed using the SAS software package (version 6.12; SAS Institute Inc, Cary, NC).

Results

The 100 subjects in the TVT group and the 100 subjects in the Uretex group were similar with respect to age, race/ethnicity, parity, prior anti-incontinence surgery, use of hormone replacement therapy, preoperative VLPP, and bladder neck hypermobility (Table 1).

Mean age was 58.2 years for subjects in the TVT group and 58.7 years for subjects in the Uretex group (P=.42). The majority of subjects in both groups were white (TVT, 80; Uretex, 84; P=.64). Mean parity was 2.5 births in the TVT group and 2.7 births in the Uretex group (P=.50). Fifteen subjects in the TVT group had prior anti-incontinence surgery, compared with 17 subjects in the Uretex group (P=.80). Postmenopausal hormone replacement therapy was used by 25 subjects in the TVT group and 30 subjects in the Uretex group (P=.54). Mean preoperative VLPP was 42.6 cm H2O in the TVT group and 41.4 cm H2O in the Uretex group (P=.60).

Perioperative complications were similar between study groups. There were two bladder perforations in the TVT group and three in the Uretex group. No subject in either group required a blood transfusion. One subject in the TVT group had an intraoperative ventricular arrhythmia that required overnight hospitalization and cardiac monitoring. All other subjects in both groups were discharged to home care on the day of surgery. In the TVT group, 20 subjects required an indwelling Foley catheter at hospital discharge, compared with 17 subjects in the Uretex group (P=.64).

No significant differences were noted when comparing postoperative complications in the TVT group with those in the Uretex group at 12-month follow-up (Table 2). Thirteen subjects in the TVT group and 10 subjects in the Uretex group had new-onset urge incontinence 12 months after surgery (P=.57). Ten subjects in the TVT group required prolonged (ie, after postoperative day 2, lasting less than 14 days total) intermittent self-catheterization at 12 months, compared with 7 subjects in the Uretex group (P=.51). Five subjects in each group had urinary retention requiring urethrolysis at 12-month follow-up (P=.99). Urinary tract infection was detected in 5 subjects in the TVT group and 4 subjects in the Uretex group (P=.62).

†At 12-month postoperative follow-up, subjects were evaluated for symptom improvement (ie, reduction of urine leakage) when performing a standing Valsalva maneuver, also known as a “cough stress test,” with a bladder volume greater than or equal to 250 cc. Although “some” urine leakage was observed for a number of subjects in both study groups, patients noted improved continence as a result of surgical intervention.

†At 12-month postoperative follow-up, subjects were evaluated for symptom improvement (ie, reduction of urine leakage) when performing a standing Valsalva maneuver, also known as a “cough stress test,” with a bladder volume greater than or equal to 250 cc. Although “some” urine leakage was observed for a number of subjects in both study groups, patients noted improved continence as a result of surgical intervention.

Among women with a history of prior anti-incontinence surgery, outcomes were also similar between groups. Fifteen women in the TVT group had undergone one prior surgical procedure (laparoscopic Burch procedure, 10; pubovaginal fascial sling, 3; TVT, 2). Seventeen women in the Uretex group reported a similar history (Burch procedure, 10; pubovaginal fascial sling, 5; TVT, 2). No subject in either study group had a history of more than one prior anti-incontinence procedure. Of the 32 women who had undergone prior anti-incontinence surgery, a little more than half (TVT, 8 [25%]; Uretex, 9 [28%]) did not leak urine during bladder stress testing at 12-month follow-up.

A small number of subjects had minimal (<30 degrees) bladder neck hypermobility (TVT, 18; Uretex, 19). Of all 37 women in both study groups, approximately half (TVT, 9 [24%]; Uretex, 10 [27%]) had no urine leakage at 12-month follow-up (P=.99). A large number of women in the study (TVT, 82; Uretex, 81) had severe (≥30 degrees) bladder neck hypermobility. Of these 163 women, the majority (TVT, 76 [93%]; Uretex, 74 [91%]) had no leakage of urine at 12-month follow-up (P=.99).

Among all study subjects, the VLPP was nearly the same, regardless of results of postoperative bladder stress testing. For women without leakage, the mean VLPP was 42.3 cm H2O. For those with postsurgical leakage, this number was 44.7 cm H2O (P=.99).

Comment

In the past decade, synthetic midurethral sling procedures have become a first-line surgical therapy for women with SUI.2-4 Although several different midurethral sling systems are commercially available, all are thought to work in a similar manner.11-13 However, little data exist comparing patient outcomes among different systems.11-13 To our knowledge, the present study is the first to compare patient outcomes for TVT vs Uretex midurethral sling systems.

Previous studies14,15 have reported lower success rates for midurethral slings in women who have less than 30 degrees of bladder neck hypermobility, as measured preoperatively via straining cotton-tipped swab test—suggesting that bladder neck hypermobility may be an important component in the mechanism of action of midurethral slings. In the present study, regardless of sling system used, surgical success rates were significantly better in women with severe vs minimal hypermobility.

Perioperative complications, based on bladder perforation rates and blood transfusion requirements, were similar between study groups. Although the trocars used to deliver each sling system into the urethra are different in shape and diameter, the same basic surgical maneuvers are used to insert both slings through the retropubic space. Therefore, one would expect the incidence of intraoperative injuries to be similar between groups. Adjusting sling tension is also similar between the sling systems tested. Because the same surgical team performed all of the procedures for both systems compared in the present study, any difference in retention rates between study groups would be explained by the type of delivery system required for each device. In the present study, however, no difference was noted in postoperative urinary retention rates between study groups. It is important to note, though, that this study may not have had sufficient statistical power to detect such a difference.

Based on 12-month outcome data, the TVT and Uretex midurethral sling systems appear to be equally effective for the treatment of women with SUI. The overall short-term success rates for both systems is higher than 90% and is similar to success rates previously reported for the TVT procedure alone.2-4 However, when results were compared for women with previous history of anti-incontinence surgery vs those without, both systems demonstrated decreased efficacy for women who had a prior surgical intervention.

The majority of subjects with prior anti-incontinence surgery had little or no bladder neck hypermobility detected on preoperative physical examination. Our finding of decreased efficacy of both the TVT and Uretex midurethral sling systems in women with minimal bladder neck hypermobility is similar to that of other researchers.9 Some authors have suggested that the mechanism of action of midurethral slings requires bladder neck hypermobility to prevent incontinence. According to this suggestion, the action of midurethral slings—as opposed to other procedures (eg, Burch procedure, pubovaginal sling)—is not an anatomic correction.9

Study Limitations

Nonrandom patient allocation to the two study groups may be seen as a limitation of the present study. In June 2002, at the beginning of the study, we were informed that the operating room at our institution would no longer purchase the TVT system and would begin, instead, to stock the Uretex system when TVT supplies ran out; the operating room staff would not stock both systems at the same time. Consequently, we could not randomly assign subjects to treatment with the TVT or Uretex system, nor could we enroll subjects in parallel with both systems. Therefore, we used the TVT system exclusively for the first 100 subjects, then switched to the Uretex system for the next 100 subjects.

Other limitations of the present study include aspects of the assessment of surgical outcomes. The cough stress test was guided and evaluated by one of the members of the surgical team, introducing the possibility of measurement bias. In addition, the cough stress test is not the optimal method for evaluating surgical outcomes of midurethral sling procedures. Optimal testing would involve repeating the multichannel urodynamic evaluations, though this processing would be invasive and cost-prohibitive. Thus, in light of the invasive nature of urodynamic testing and the additional cost associated, we believe that the cough stress test can provide a reasonable assessment of SUI severity in most clinical settings.

Conclusion

As the number of different midurethral sling procedures continues to increase, it is important that each system be evaluated carefully to determine its clinical effectiveness before widespread adoption. In the present nonrandomized study, the TVT and Uretex midurethral sling systems demonstrated similar perioperative morbidity and 12-month success rates. The short-term success rates of both systems were significantly higher in women who had severe rather than minimal bladder neck hypermobility. Further studies are necessary to evaluate the long-term efficacy of the Uretex midurethral sling system.

†At 12-month postoperative follow-up, subjects were evaluated for symptom improvement (ie, reduction of urine leakage) when performing a standing Valsalva maneuver, also known as a “cough stress test,” with a bladder volume greater than or equal to 250 cc. Although “some” urine leakage was observed for a number of subjects in both study groups, patients noted improved continence as a result of surgical intervention.

†At 12-month postoperative follow-up, subjects were evaluated for symptom improvement (ie, reduction of urine leakage) when performing a standing Valsalva maneuver, also known as a “cough stress test,” with a bladder volume greater than or equal to 250 cc. Although “some” urine leakage was observed for a number of subjects in both study groups, patients noted improved continence as a result of surgical intervention.